I've used an Osprey 44 for quite a few of 1-3 nighters now, it's a top loader but it's got a bottom zipper too, so I pack my tent/tarp in the bottom so I can get them out fast in case of rain.

I like the bottom zipper. It's nice to be able to get my tent or tarp out first when I'm setting up camp, even when it's not raining. Without it, I might consider putting my tarp or tent on top if there were a good chance of rain.

I'll get into my pack several times a day before setting up camp, so I try to keep the things I need most near the top, but it seems I always end up digging for something I buried in the pack. I haven't found any way around it so I just don't fret about it anymore.